Internal Combustion Engine With Integrated Waste Heat Recovery System

ABSTRACT

An engine assembly may include a first heat exchanger, a fluid supply system providing a fluid flow to the first heat exchanger, a fuel system, an engine block defining first and second cylinder bores, a first piston disposed within the first cylinder bore, and a second piston disposed within the second cylinder bore. The first cylinder bore may receive fuel from the fuel system for combustion therein to drive the first piston. The fluid flow may be pressurized within the first heat exchanger and the pressurized fluid may be provided to the second cylinder bore to drive the second piston.

FIELD

The present disclosure relates to engine assemblies including waste heat recovery systems.

BACKGROUND

This section provides background information related to the present disclosure which is not necessarily prior art.

Engine assemblies may include waste heat recovery systems to utilize heat produced by an engine. These systems may typically include an auxiliary expander device in fluid communication with a fluid heated by the engine. In order to couple the power generated by the expander to the engine, complicated coupling devices may be required. Additionally, the use of an auxiliary expander may generate excessive cost and packaging demands, as well as additional complexity for assembly.

SUMMARY

This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

An engine assembly may include a first heat exchanger, a fluid supply system providing a fluid flow to the first heat exchanger, a fuel system, an engine block defining first and second cylinder bores, a first piston disposed within the first cylinder bore, and a second piston disposed within the second cylinder bore. The first cylinder bore may receive fuel from the fuel system for combustion therein to drive the first piston. The fluid flow may be pressurized within the first heat exchanger and the pressurized fluid may be provided to the second cylinder bore to drive the second piston.

A method may include providing a fuel supply to a first cylinder bore of an engine block and igniting the fuel supply to power displacement of a first piston located in the first cylinder bore. The method may further include providing a fluid flow to a first heat exchanger to pressurize the fluid flow therein and providing the pressurized fluid flow to a second cylinder bore of the engine block to power displacement of a second piston locating in the second cylinder bore.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

FIG. 1 is a schematic illustration of an engine assembly according to the present disclosure; and

FIG. 2 is a schematic illustration of an alternate engine assembly according to the present disclosure.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference to the accompanying drawings.

With reference to FIG. 1, an engine assembly 10 may include an engine block 12, an air intake system 14, an exhaust system 16, an engine cooling system 18, a fuel system 20 and a waste heat recovery system 22. The engine block 12 may define cylinder bores 24 having pistons 26 disposed therein and coupled to a crankshaft 28. The engine block 12 may be formed as a unitary casting. The present non-limiting example illustrates an inline four cylinder engine configuration where first and second cylinder bores 24 a, 24 b are combustion cylinders and third and fourth cylinder bores 24 c, 24 d are pressure operated cylinders.

The air intake system 14 may include an intake manifold 30 in fluid communication with an air source 32 and the first and second cylinder bores 24 a, 24 b. The air intake system 14 may be isolated from the third and fourth cylinder bores 24 c, 24 d. The fuel system 20 may provide a fuel flow to the first and second cylinder bores 24 a, 24 b. The exhaust system 16 may include an exhaust manifold 34 in fluid communication with the first and second cylinder bores 24 a, 24 b and may be isolated from the third and fourth cylinder bores 24 c, 24 d. The exhaust manifold 34 may be in fluid communication with and provide an exhaust gas flow 36 from the first and second cylinders 24 a, 24 b to the waste heat recovery system 22, as discussed below.

The engine cooling system 18 may include a coolant reservoir 38, a coolant pump 40, a thermostat valve 42, a heat exchanger 44 and a cabin heater 46. The coolant pump 40 may pump engine coolant from the coolant reservoir 38 through coolant passages (not shown) in the engine block 12 and then back to the coolant reservoir 38. As the engine coolant passes through the engine block 12, the coolant absorbs heat. The heated engine coolant is returned to the coolant reservoir 38, as discussed above.

Before being returned to the engine block 12, the engine coolant flows through the cabin heater 46 and/or the heat exchanger 44. The cabin heater 46 and heat exchanger 44 may reduce a temperature of the coolant. More specifically, the cabin heater 46 may transfer the heat from the coolant to a vehicle interior. The heat exchanger 44 may additionally form part of the waste heat recovery system 22, as discussed below. The amount of coolant flow passing through the heat exchanger 44 may be controlled by the thermostat valve 42.

The waste heat recovery system 22 may include a fluid supply system 48 in fluid communication with a heat exchanger 50. The fluid supply system 48 may include a pump 52, a reservoir 54, and first and second control valves 56, 58. The reservoir 54 may contain a fluid used the waste heat recovery system 22. By way of non-limiting example, the fluid may include water. The reservoir 54 may additionally include a condenser to convert the fluid from a vapor form to a liquid. The heat exchanger 50 may include a first flow path 60 in fluid communication with the exhaust gas flow 36 exiting the first and second cylinders 24 a, 24 b and a second flow path 62 in fluid communication with the fluid from the fluid supply system 48. The second flow path 62 may additionally be in fluid communication with the third cylinder 24 c.

During operation, the fluid supply system 48 may force the fluid through the second flow path 62 in the heat exchanger 50, where the exhaust gas 36 heats the fluid. The fluid may change from a liquid to a vapor based on the heating in the heat exchanger 50. When the fluid transitions from liquid to the vapor, it may expand, increasing in pressure. The vapor is supplied to the third cylinder 24 c where the increased pressure is applied to the piston 26 to assist in driving rotation of the crankshaft 28. The amount of vapor supplied to the third cylinder 24 c may be controlled by the first control valve 56. Excess vapor may return to the reservoir 54 through the second control valve 58.

After the power stroke of the third cylinder 24 c is completed, the fluid may remain in the vapor state, and may therefore be used to power displacement of another piston 26. More specifically, the third and fourth cylinders 24 c, 24 d may be in fluid communication with one another. Flow from the third cylinder 24 c to the fourth cylinder 24 d may be controlled by a third control valve 64. The exhaust stroke of the piston 26 within the third cylinder 24 c may provide the exhaust flow from the third cylinder 24 c to the fourth cylinder 24 d, where the piston 26 in the fourth cylinder 24 d is displaced based on a pressure provided by the exhaust vapor from the third cylinder 24 c. During the exhaust stroke of the piston 26 within the fourth cylinder 24 d, the remaining vapor and/or liquid may be returned to the reservoir 54.

In the present non-limiting example, the fluid flow may be provided to the heat exchanger 50 by the pump 52. The fluid may first pass through the heat exchanger 44 of the cooling system 18 to provide an additional heat source for the fluid before passing through the heat exchanger 50. Additionally, in the present non-limiting example, the first and second cylinders 24 a, 24 b (combustion cylinders) may be directly adjacent one another. The first and second cylinders 24 a, 24 b are generally located between the third and fourth cylinders 24 c, 24 d.

It is understood that while the first and third control valves 56, 64 are schematically illustrated, each may be similar to an intake valve of an engine. Specifically, each of the first and third control valves 56, 64 may be engaged with an engine camshaft (not shown) and may therefore be mechanically controlled. Further, while the engine assembly 10 is illustrated as an inline four-cylinder configuration, it is understood that the present teachings apply to a variety of other engine configurations including V-engines and horizontally opposed engines, as well as engines having more or less cylinders. For example, FIG. 2 illustrates the present teachings employed in an inline six cylinder arrangement.

Referring now to FIG. 2, an alternate engine assembly 100 is schematically illustrated. As indicated above, the engine assembly 100 generally depicts an inline six cylinder engine employing a waste heat recovery system 122 generally similar to the waste heat recover system 22 of FIG. 1. The engine assembly 100 may be generally similar to the engine assembly 10 shown in FIG. 1. Therefore, it is understood that the description above generally applies with the exceptions noted below.

The engine assembly 100 may include an engine block defining first, second, and third cylinders 124 a, 124 b, 124 c (combustion cylinders) in fluid communication with the fuel system 120 and fourth, fifth, and sixth cylinders 124 d, 124 e, 124 f in fluid communication with the waste heat recovery system 122. The fourth cylinder 124 d may first receive the vapor from the waste heat recovery system 122 and the fifth and sixth cylinders 124 e, 124 f may receive exhaust vapor from the fourth cylinder 124 d. Control valves 166, 168 may control fluid communication between the fourth cylinder 124 d and the fifth and sixth cylinders 124 e, 124 f.

In the inline six cylinder example shown in FIG. 2, the first, second, and third cylinders 124 a, 124 b, 124 c (combustion cylinders) may be directly adjacent one another. The fourth, fifth, and sixth cylinders 124 d, 124 e, 124 f may each be directly adjacent to one another as well. 

1. An engine assembly comprising: a first heat exchanger; a fluid supply system providing a fluid flow to the first heat exchanger, the fluid flow being pressurized within the first heat exchanger; a fuel system; an engine block defining first and second cylinder bores, the first cylinder bore receiving fuel from the fuel system for combustion therein and the second cylinder bore receiving pressurized fluid exiting the first heat exchanger; a first piston disposed within the first cylinder bore and being reciprocally displaced by combustion within the first cylinder bore; and a second piston disposed within the second cylinder bore and being reciprocally displaced by the pressurized fluid.
 2. The engine assembly of claim 1, wherein an exhaust gas produced by the combustion within the first cylinder bore is in fluid communication with the first heat exchanger, the exhaust gas providing a heat source to the first heat exchanger to raise the pressure of the fluid flow passing through the first heat exchanger.
 3. The engine assembly of claim 1, wherein the fluid flow enters the first heat exchanger as a liquid and exits the first heat exchanger as a vapor.
 4. The engine assembly of claim 3, wherein the fluid flow entering the first heat exchanger includes liquid water and the fluid flow exiting the first heat exchanger includes steam.
 5. The engine assembly of claim 1, further comprising an engine cooling system including a second heat exchanger having a engine coolant passing therethrough, the fluid supply system being in fluid communication with the second heat exchanger, the fluid flow being heated by the engine coolant passing through the second heat exchanger.
 6. The engine assembly of claim 1, wherein the engine block includes a third cylinder bore having a third piston disposed therein, the third cylinder bore receiving exhaust from the second cylinder bore to reciprocally drive the third piston.
 7. The engine assembly of claim 6, wherein the engine block includes a fourth cylinder bore having a fourth piston disposed therein, the fourth cylinder bore receiving fuel from the fuel system for combustion therein to reciprocally drive the fourth piston, the first and fourth cylinder bores being directly adjacent one another.
 8. The engine assembly of claim 7, wherein the second cylinder bore is adjacent to the first cylinder bore and the third cylinder bore is adjacent to the fourth cylinder bore.
 9. The engine assembly of claim 7, wherein the second and third cylinder bores are directly adjacent to one another.
 10. The engine assembly of claim 1, further comprising a crankshaft, the crankshaft engaged with and rotationally driven by the first and second pistons.
 11. An engine waste heat recovery system comprising: a first heat exchanger; and a fluid supply system providing a fluid flow to the first heat exchanger, the fluid flow being pressurized within the first heat exchanger and provided to a first cylinder bore of an engine block to drive a first piston disposed therein, the engine block defining a second cylinder bore having a second piston disposed therein driven by combustion of fuel therein.
 12. The engine waste heat recovery system of claim 11, wherein the first heat exchanger is in fluid communication with an exhaust gas from the second cylinder bore, the exhaust gas providing a heat source to the first heat exchanger to raise the pressure of the fluid flow passing through the first heat exchanger.
 13. The engine waste heat recovery system of claim 11, wherein the fluid flow enters the first heat exchanger as a liquid and exits the first heat exchanger as a vapor.
 14. The engine waste heat recovery system of claim 13, wherein the fluid flow entering the first heat exchanger includes liquid water and the fluid flow exiting the first heat exchanger includes steam.
 15. The engine waste heat recovery system of claim 11, further comprising a second heat exchanger, the second heat exchanger being in fluid communication with an engine coolant and the fluid supply system, the fluid flow being heated by the engine coolant passing through the second heat exchanger.
 16. A method comprising: providing a fuel supply to a first cylinder bore of an engine block; igniting the fuel supply to power displacement of a first piston located in the first cylinder bore; providing a fluid flow to a first heat exchanger to pressurize the fluid flow therein; and providing the pressurized fluid flow to a second cylinder bore of the engine block to power displacement of a second piston locating in the second cylinder bore.
 17. The method of claim 16, further comprising providing an exhaust gas from the first cylinder bore to the first heat exchanger to pressurize the fluid flow within the first heat exchanger.
 18. The method of claim 16, wherein the pressurization of the fluid flow includes heating the fluid flow to transform the fluid flow from a liquid to a vapor.
 19. The method of claim 16, wherein the providing a fluid flow includes providing water to the first heat exchanger and the pressurized fluid flow provided to the second cylinder bore includes steam.
 20. The method of claim 16, further comprising providing the pressurized fluid flow exiting the second cylinder bore to a third cylinder bore of the engine block during an exhaust stroke of the second piston. 